What LaTeX is trying to do with this:
\documentclass{article}
\usepackage{floatflt}
\begin{document}
\begin{floatingtable}[r]{
\begin{tabular}{cc}
0 & 1 \\
1 & 0
\end{tabular}}
\end{floatingtable}
This is MWE.
\end{document}
I got
Underfull \hbox (badness 10000) in paragraph at lines 9--10
and message disappears if I add \raggedright after \begin{document}. It does not make any difference if I add more words to "This is MWE." -paragraph or add few paragraphs more.

\centeringjust after the opening brace:\begin{floatingtable}[r]{\centering...– egreg May 07 '13 at 09:42\centering. – Jori Mäntysalo May 07 '13 at 13:49Underfull \vboxis exactly the one built by\floatingtable. – egreg May 07 '13 at 15:24